Cartridge-fuse.



A. L. EUSTICE.

CARTRIDGE FUSE.

APPUCAUON man JULY 23,1914.

1,18936? mmmw. :25, 1916.

inserer.

{applic-ation 5 of illinois, have invented. certain new and useful linprovernents in lartridgednses, oi' which the 'following is a speciiication.

My'invention relates to cartridge fuses, and, refers particularly (although not clusively) to renewable cartridge uses of the errule type.

l am aware that renewable Aerrule type fuses are well known, as shown, for example,`

in the 'following United States patents: No. 861,965, issued to C. Gehrke July 30, 1907 No. 961,716, issued to A. l?. Daum lune lei., 1910; No.1,022,834l, April 9, 1912; No. 1,092,498, issued to E. B. MalloryApril 7, 1914. All ot these patents show electrical safety fuses in which the fusible element may be renewed on removal oi"4 retaining members located at the ends oli the casing. The results obtained in fuses such as are shown in the patents ahove mentioned have not proved entirely satisfactory, either on account of the complicated construction of the fuse or on account of the 'iact that after the various parts of the fuse are assembled they become loosened by shrinkage of the casing (ordinarily made or Eher) or other similar cause. Still another defect of these fuses has heen that their construction was siich that their rating,` did not prove to he accurate when subjected to overload conditions, and they were apt to Vent fire when suojected to violent short-circuit conditions.

lt is the object of my invention to construct a 'fuso which is cheap and simple to manufacture, which is elicicnt when blown under either overload or short-circuit conditions, and the parts of which will remain in tight-contact with each other irrespective of any shrinkage which might occur in connection with the insulating liber casing.

My improved fuse is so designed that it is Yunnecessary to employ a non-,conducting lilling material of asbestos, lime, or the like. The parts are so constructed that on blowing of the fuse under short-circuit the gases formed are restricted in their escape issued to S. F. Estell.

Specification or Letters Serial We. 532,551

from inse casing, with the resultthat the operation of the fuse is noiseiess while at the same time the venting or :Eire is electually prevented. l preferably construct the usiblelinlr with two or more restricted por? tions or less cross-sectional aree tlientlie halanee'o the link so that on blowing the fuse t `e portion the link between these restricted. poi"'ons drops out of the link, thereby reducing the volatilization of metal to a minimum.

and other advantages of my invention will loe more readily understood by reference to the accompanying drawings, in whichl Figure l is a longitudinal section through my improved 'use; Fig. 2 is a section taken on the line 2-2 of Fig. l; Fig. 3 is an end elevation oic the fuse shown in Figs. l and 2; Fig. e is a transverse section taken on the line lf-4.- oi Fig'. l; Fig. 5 is a transverse section taken on the line 5-5 of Fig. 1; Fig. 6 is a perspective of the fusible link; and Fig. 7 is an enlarged fragmentary longitudinal section through the end of the casing and a portion oit' the icerrule showing the clearance between the threaded portions of these elements.

My improved fuse is provided with the casing l0, of liber or other suitable insulating material, the ends of the casing 10 having thereon the threa'dsll. A errule 12 is applied to each end of the casing 10 and has threaded engagement therewith, a slight clearance i3 being provided between the threads 11 of the'casing 10 and the threads oi" the 'fel-rule 12. llach feriaile 'l2 is provided with an inwardly extending retaining flange i4, which engages the end of the casing l() after the ferrule 12 has been screwed into position. To prevent rotation of the ferrule 12 in either direction with respect to the casing'll, the lugs 15 are forced from the metal o the retaining flanges 14 into the fiber at the ends of the casing l0, this operation being performed by any sintable tool. after the errule l2 has been screwed into position. A permanent connection between the casing l0 and the ferrul'es l2 is thus provided. it each end of t e fuse a washer i6 having the slot 17 is located gust outside of the retaining liange 1l and engages the latter. The fusible link 1.3 passes thrmigh the slot 1T and has its end l) bent over the outer surface oi the washer lo. As clearly shown in Figs. 3. si and (l, the bent-over end 19 of the link 18 preferably stamped .with a number indicating the (alpacity of the fuse in amperes. The washers 1G do not have threaded engagement with the ferrules 1Q but are freely movable iu the outer threaded portions of these ierrules so that they may be quickly applied to or removed from their positions in engagement with the flanges l-l.

iit each end oi' the l'use is a plug Q0 which has threaded engagement with the inner surface of the outer end oi' the ferrul'e 12. lAs clearly shown in Fig. 7. there is a slight clearance 13u between the. threads of the plugs Q and the threads ot the outer portions of the ferrules l2. rl`he plug 20 is provided with a slot .21 which may be engaged by a screw driver or other xsuitable tool so that the plug may readily be screwed home. The plug also preferably hasan aperture 22 through its central portion through which the number on the over-turned end 15) of the fuse link may be readily risible. Then screwed into position the plug ZOfengages the over-turned end 19 of the fuse link and Jforces it into tight contact with the washer 16. This washer at the same time is forced into tight engagement with the retaining flange 14. The i'errules 12, the washers 1G, and the plugs 20 are preferably made of a readily conducting metal, such as brass or copper, and it will be evident that by the construction just described these parts are maintained i engagement with each other andA withl the over-turned end of the fusible link by a metal-to-metal contact, and if shrinkage of, the casing 10 occurs the engagement of the ferrules 12 with the washers 16, the ends 19 of the link 18, and the plugs 20 is not affected. In this way good electrical Contact is always maintained between these parts,`and unsatisfactory performance of a fuse on`account of loose contacts is el'- fectively avoided.

The fusible link 1S is preferably flat and piovided \vit h the restricted portions 223. On blowing of the fuse the latter meltsat these restricted portions, causing the section of link between the restricted portions to drop out of the link, thereby avoiding volatilization ou a large amount ot the i'netal of' which. the link composed. Atteithe fuse is blown a new link 18 may readily be placed in position byirst removing the plugs 20 and then removing the washers 1G. One end of the new link is then bent, passed through the slot 1'? ol' a washer 1G, and the washer lis placed in position in engagement with the retaining ilange 141, thereby causing the link to extend through the casing 10. The plug tween the threads 11 of the casing and the` threads of the inner ends of the ferrules 12 and between the threads of the plugs 2O and the threads of the outer ends of the er' rules 12, respectively. I have found by experience that the clearance spaces 13 are more emcient than the clearance spaces 13, as the former are between metal parts and are less liable to distortion. Inasmuch as the gases are thus restricted in their passage to the exterior the device acts according to the same principle as the well-known Maxim silencer or an automobile muiiler, thereby preventing the noise of an explosion and preventing the venting of fire.

It will be apparent to those skilled in the art that many changes `may be made in the detailed construction of the Various parts which I have described Without departing from the spirit or scope of my invention.

VJhat I claim is:

1. In a cartridge fuse, the combination of a cylindrical casing, fel-rules at the ends of said casing, each of said ferrules having engagement with the corresponding end of said casing, retaining means on the inner periphery of each of said fcrrules, means for preventing rotation of said ferrules with respect to said casing, a washer freely insertible in the outer end of each of said ferrules and engaging said retaining means, a link passing through said casing and having its ends bent over the outersurfaces of said washers, and a plug in the outer end of each tei-rule, said plugs engaging the bent-over ends of said link and forcing said washers into tight engagement with said retaining means. 4

2. In a cartridge fuse, the combination of a casing, a ferrule at each end of said casing and having threaded engagement therewith, a retaining flange formed on the inner periphery of each of said errules, said retain-` ing flange engaging an end of said casing, lugs formed in said retaining fiange and passing into the body of said casing, whereby relative rotation of said ferrule and said rasing is prevented., an apertured washer freely insertible in the outer end of said ierrule and engaging said retaining flange, a link passing through said casing and the apertures in said washers and having its ens bent over the outensurfces of .said Washers, and a plug in the outer 'end of each ferrule and having threaded engagement-- therewith, said plugs engaging the bent-over ends of said link and forcing said-washers mto'tlght engagement with said retaining flange.

In Witness whereof, I hereunto subscribe A my name this 11th day of July, A. D., 1514.

ALFRED L. EUSTCE.

Witnesses:

JAMES A. Simms, W. E. REQUXSA. 

